Well after nearly being hit or hitting 4 deer in my first 1,500 miles this season and then having one jump out and try to go over my bike hitting and nearly pealing my wife off the back, I decided to put an electronic deer whistle on my 07 ultra. I have since noticed that when I see deer in the field they tend to pick up there head, look and either stay put or run the other way. People riding with me have also told me they have seen the same thing. If its the deer whistle or not??? who knows... but I can say that prior to the whistle they never seemed to react at all. Kinda ugly so I mounted it low on the left engine guard. I know its giving us a little more peace of mind anyway... Deer heard is out of control here in Michigan...